Radiation-curable compounds

ABSTRACT

The invention relates to low-viscosity formulations of radiation-curable compounds, to processes for preparing them, to their use, and to inks, printing-inks, and print varnishes that comprise them.

The invention relates to low-viscosity formulations of radiation-curablecompounds, to processes for preparing them, to their use, and to inks,printing-inks, and print varnishes that comprise them.

U.S. Pat. No. 3,429,852, U.S. Pat. No. 3,214,492, U.S. Pat. No.3,622,848, and U.S. Pat. No. 4,304,895 disclose acetophenone andbenzophenone derivatives as photoinitiators, which are joined—optionallyvia a spacer group—to a (meth)acrylate group and which therefore areincorporable in a radical polymerization.

DE 19501025 discloses vinyloxycarbonyl groups which are bonded tophotoinitiator systems and which are likewise incorporable in a radicalpolymerization.

Because of the limited possibilities of the spacer structures, however,the compounds disclosed therein are variable only within narrow limits.Moreover, such compounds are often not completely reacted in the courseof the UV polymerization, and may consequently migrate from the coating.

WO 03/68785 discloses reactions of acylphosphine oxide-typephotoinitiators with diisocyanates. More extensive functionalization ofthe free isocyanate groups is not disclosed.

WO 03/68783 discloses reactions of optionally hydroxyalkylatedacylphosphine oxide photoinitiators with diisocyanates andpolyisocyanates. More extensive functionalization of the free isocyanategroups is not disclosed.

EP 632329 discloses photoinitiators of the benzophenone, acetophenone orhydroxyacetophenone type which are functionalized with diisocyanates.The resulting isocyanates can subsequently be derivatized further, asfor example by reaction of the free isocyanate group with hydroxyalkyl(meth)acrylates, to give photoinitiators which are incorporable in aradical polymerization.

A disadvantage of this functionalization is that, as a result of the useof diisocyanates, only a low degree of functionalization can beachieved.

DE 10 2006 047 863 A1 describes the attachment of photoinitiators topolyisocyanates for the purpose of rendering them incorporable.

A disadvantage is that the resultant products still have a relativelyhigh viscosity, thereby hindering their incorporability andmultivalidiness in coating materials, and more particularly inprinting-inks and print varnishes. Moreover, the preparation examplesdisclosed make use exclusively of dibutyltin dilaurate, which istoxicologically objectionable.

WO 00/39183 describes polyisocyanates which contain allophanate groupsand carry radically polymerizable, activated C═C double bonds.

DE 102 46 512 describes a different process for preparing the samecompounds as described in WO 00/39183, and also various derivatives ofsuch compounds. Also disclosed is the chemical coupling ofpolymerization stabilizers by way of free isocyanate groups.

A disadvantage of these polyisocyanates is that for radiation curingwith UV they require the addition of a photoinitiator. Ifphotoinitiators are added as separate components, there is, first, aneed for an additional metering step, and there is, second, an attendantrisk of mismetering. Moreover, in the low molecular mass photoinitiatorsmetered in, there is a risk that they may migrate from the cured coatingand accordingly, in the case of use in UV-curable printing-inks forpackaging, may pass onto the contents.

It was an object of the present invention to provide photoinitiatorswhich exhibit maximum incorporability into radiation-curable coatingmaterials, and especially inks, printing-inks, and print varnishes, anda relatively low migration tendency, while at the same time having alower viscosity than comparable products from the prior art. Moreover,the incorporable photoinitiators are not to contain any toxicologicallyobjectionable substances that oppose their usefulness in packaging forfood and drink, for example.

This object has been achieved by means of a process for preparingincorporable photoinitiators of low viscosity, comprising the steps of

1) synthesizing a polyurethane A comprising as synthesis components

-   -   (a) at least one polyisocyanate containing allophanate groups        and having an NCO functionality of at least 2, synthesized from        aliphatic C₄ to C₂₀ alkylene diisocyanates,    -   (b) at least one compound having in each case at least one        isocyanate-reactive group and at least one radically        polymerizable unsaturated group,    -   (c) at least one photoinitiator having at least one        isocyanate-reactive group,    -   (d) optionally at least one further diisocyanate and/or        polyisocyanate, which is different from the compound (a),    -   (e) optionally at least one compound having at least two        isocyanate-reactive groups, and also    -   (f) optionally at least one compound having precisely one        isocyanate-reactive group        under anhydrous conditions, wherein the polyurethanes (A) are        prepared in the presence of less than 1000 ppm by weight of a        bismuth-, zinc- and/or titanium-containing compound and in a        step 2) the polyurethane (A) obtained from step 1) is mixed with        0.5% to 4% by weight of water, based on the amount of        polyurethane (A).

The reaction mixtures obtained when preparing the polyurethanes of theinvention generally have a number-average molar weight M_(n) of lessthan 10 000 g/mol, preferably of less than 5000 g/mol, more preferablyof less than 4000, and very preferably of less than 2000 g/mol(determined by gel permeation chromatography using tetrahydrofuran andpolystyrene as standard).

In one preferred embodiment of the invention the polyurethanes of theinvention no longer contain virtually any free isocyanate groups, i.e.,the amount of free isocyanate groups is less than 0.5% by weight,preferably less than 0.3%, more preferably less than 0.2%, verypreferably less than 0.1%, and more particularly less than 0.05%, andespecially 0% by weight.

Component (a) comprises polyisocyanates which contain allophanate groupsand have an NCO functionality of at least 2, preferably of 2 to 5, andmore preferably of 2 to 4. The polyisocyanates (a) containingallophanate groups are synthesized from aliphatic C₄ to C₂₀ alkylenediisocyanates, preferably from hexamethylene 1,6-diisocyanate.

With particular preference, component (b) is bonded via allophanategroups to component (a).

In accordance with the invention the polyurethanes (A) may containallophanate groups, the amount of allophanate groups in suchpolyurethanes of the invention being preferably (calculated asC₂N₂HO₃=101 g/mol) 1% to 28% by weight, preferably from 3% to 25% byweight.

In one preferred embodiment of the present invention, of the compounds(b) having in each case at least one isocyanate-reactive group and atleast one radically polymerizable unsaturated group that form synthesiscomponents of the polyurethanes (A) of the invention, at least 20 mol %,preferably at least 25 mol %, more preferably at least 30 mol %, verypreferably at least 35 mol %, more particularly at least 40 mol %, andespecially at least 50 mol % are bonded to allophanate groups.

In one particularly preferred embodiment the compound in question is apolyisocyanate which contains allophanate groups and has the formula (I)

in which n is a positive number which is on average 1 up to 5,preferably from 1 to 3.

Contemplated as component (b) in accordance with the invention is atleast one compound (b) which carries at least one isocyanate-reactivegroup and at least one radically polymerizable group.

The compounds (b) preferably have precisely one isocyanate-reactivegroup and 1 to 5, more preferably 1 to 4, and very preferably 1 to 3radically polymerizable groups.

The components (b) preferably have a molar weight of below 10 000 g/mol,more preferably below 5000 g/mol, very preferably below 4000 g/mol, andmore particularly below 3000 g/mol. Special components (b) have a molarweight of below 1000 or even below 600 g/mol.

Isocyanate-reactive groups may be, for example, —OH, —SH, —NH₂, and—NHR¹, where R¹ is hydrogen or an alkyl group containing 1 to 4 carbonatoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,sec-butyl or tert-butyl, for example.

Components (b) may be, for example, monoesters of α,β-unsaturatedcarboxylic acids, such as acrylic acid, methacrylic acid, crotonic acid,itaconic acid, fumaric acid, maleic acid, acrylamidoglycolic acid andmethacrylamidoglycolic acid, which have preferably 2 to 20 C atoms andat least two hydroxyl groups, such as ethylene glycol, diethyleneglycol, triethylene glycol, propylene 1,2-glycol, propylene 1,3-glycol,1,1-dimethyl-1,2-ethanediol, dipropylene glycol, triethylene glycol,tetraethylene glycol, pentaethylene glycol, tripropylene glycol, 1,2-,1,3- or 1,4-butanediol, 1,5-pentanediol, neopentyl glycol,1,6-hexanediol, 2-methyl-1,5-pentanediol, 2-ethyl-1,4-butanediol,1,4-dimethylolcyclohexane, 2,2-bis(4-hydroxycyclohexyl)propane,glycerol, trimethylolethane, trimethylolpropane, trimethylolbutane,pentaerythritol, ditrimethylolpropane, erythritol, sorbitol,polyethylene glycol having a molar mass of between 106 and 2000,polypropylene glycol having a molar weight of between 134 and 2000,polyTHF having a molar weight of between 162 and 2000 orpoly-1,3-propanediol having a molar weight of between 134 and 400. Inaddition it is also possible to use esters or amides of (meth)acrylicacid with amino alcohols such as 2-aminoethanol, 2-(methylamino)ethanol,3-amino-1-propanol, 1-amino-2-propanol or 2-(2-aminoethoxy)ethanol, forexample, 2-mercaptoethanol or polyaminoalkanes, such as ethylenediamineor diethylenetriamine, or vinylacetic acid.

Also suitable, furthermore, albeit less preferably, are unsaturatedpolyetherols or polyesterols or polyacrylate polyols having an averageOH functionality of 2 to 10.

Examples of amides of ethylenically unsaturated carboxylic acids withamino alcohols are hydroxyalkyl(meth)acrylamides such asN-hydroxymethylacrylamide, N-hydroxymethylmethacrylamide,N-hydroxyethylacrylamide, N-hydroxyethylmethacrylamide,5-hydroxy-3-oxapentyl(meth)acrylamide, N-hydroxyalkylcrotonamides suchas N-hydroxymethylcrotonamide, or N-hydroxyalkylmaleimides such asN-hydroxyethylmaleimide.

Preference is given to using 2-hydroxyethyl (meth)acrylate, 2- or3-hydroxypropyl (meth)acrylate, 1,4-butanediol mono(meth)acrylate,neopentyl glycol mono(meth)acrylate, 1,5-pentanediol mono(meth)acrylate,1,6-hexanediol mono(meth)acrylate, glycerol mono(meth)acrylate anddi(meth)acrylate, trimethylolpropane mono(meth)acrylate anddi(meth)acrylate, pentaerythritol mono(meth)acrylate, di(meth)acrylate,and tri(meth)acrylate, and also 2-aminoethyl (meth)acrylate,2-aminopropyl (meth)acrylate, 3-aminopropyl (meth)acrylate, 4-aminobutyl(meth)acrylate, 6-aminohexyl (meth)acrylate, 2-thioethyl (meth)acrylate,2-aminoethyl(meth)acrylamide, 2-aminopropyl(meth)acrylamide,3-aminopropyl(meth)acrylamide, 2-hydroxyethyl(meth)acrylamide,2-hydroxypro-pyl(meth)acrylamide, or 3-hydroxypropyl(meth)acrylamide.Particularly preferred are 2-hydroxyethyl acrylate, 2-hydroxyethylmethacrylate, 2- or 3-hydroxypropyl acrylate, 1,4-butanediolmonoacrylate, 3-(acryloyloxy)-2-hydroxypropyl (meth)acrylate, and alsothe monoacrylates of polyethylene glycol with a molar mass of 106 to238.

In one preferred embodiment, component (b) may also comprise technicalmixtures from the acrylation of trimethylolpropane, pentaerythritol,ditrimethylolpropane or dipentaerythritol, or alkoxylated, preferablypropoxylated and/or ethoxylated, more preferably ethoxylated,trimethylolpropane, pentaerythritol, ditrimethylolpropane ordipentaerythritol. These are mostly mixtures of completely andincompletely acrylated polyols; for example, compounds (b) are technicalmixtures from the acrylation of pentaerythritol that usually have an OHnumber to DIN 53240 of 99 to 115 mg KOH/g and consist predominantly ofpentaerythritol triacrylate and pentaerythritol tetraacrylate, and mayalso contain minor amounts of pentaerythritol diacrylate. This has theadvantage that pentaerythritol tetraacrylate is not incorporated intothe polyurethane of the invention, but instead functions simultaneouslyas a reactive diluent.

Component (c) is at least one photoinitiator having at least oneisocyanate-reactive group, preferably at least one photoinitiator of theα-hydroxyacetophenone type or benzophenone type, in each case having atleast one isocyanate-reactive group, and more preferably at least onephotoinitiator of the α-hydroxyacetophenone type.

A photoinitiator for the purposes of this specification is a compoundwhich can be cleaved into at least one radical by electromagneticradiation, preferably by UV radiation, visible light or IR radiation,more preferably by UV radiation or visible light, and very preferably byUV radiation.

Component (c) may comprise one or more than one—for example, 1 to 3,preferably 1 to 2, and more preferably precisely one—group which isactive as a photoinitiator, preferably α-hydroxyacetophenone group orbenzophenone group, more preferably α-hydroxyacetophenone group.Moreover, component (c) may comprise one or more than one—for example, 1to 4, preferably 1 to 3, more preferably 1 to 2 and very preferablyprecisely one—isocyanate-reactive group.

The groups which are active as photoinitiators may preferably behydroxybenzophenones or hydroxyacetophenones, and more preferablyhydroxyacetophenones.

Preferred components (c) are

in whichR³, R⁴, and R⁵ each independently of one another are hydrogen, an alkylgroup containing 1 to 4 carbon atoms or an alkyloxy group containing 1to 4 carbon atoms,p may be 0 (zero) or an integer from 1 to 10, andY_(i) for i=1 to p independently of one another may be selected from thegroup of —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, —CH(CH₃)—CH₂—O—, —CH₂—C(CH₃)₂—O—,—C(CH₃)₂—CH₂—O—, —CH₂—CHVin-O—, —CHVin-CH₂—O—, —CH₂—CHPh-O—, and—CHPh-CH₂—O—, preferably from the group of —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—,and —CH(CH₃)—CH₂—O—, and more preferably —CH₂—CH₂—O—.

The group —O—[—Y_(i)—]_(P)—H is preferably located in para-position tothe carbonyl group.

The radicals R³, R⁴, and R⁵ independently of one another are preferablyhydrogen or methyl, more preferably hydrogen.

Preferably p is 0 to 4, more preferably it is 1 to 3, and verypreferably it is 1.

Preferred components (c) are 2-hydroxy-2-methyl-1-phenyl-propan-1-one,1-hydroxycyclohexyl phenyl ketone,1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one,2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one,2-hydroxy-1-[4-[hydroxy[4-(2-hydroxy-2-methyl-propanoyl)phenyl]methyl]phenyl]-2-methyl-propan-1-one,[4-[3-(4-benzoylphenoxy)-2-hydroxypropoxy]phenyl]phenylmethanone,benzoin, benzoin isobutyl ether, benzoin tetrahydropyranyl ether,benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoinisopropyl ether, 7H-benzoin methyl ether,2-hydroxy-2,2-dimethylacetophenone, or 1-hydroxyacetophenone.

Particularly preferred are1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one,2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methyl-propan-1-one,and2-hydroxy-1-[4-[hydroxy-[4-(2-hydroxy-2-methylpropanoyl)phenyl]-methyl]phenyl]-2-methylpropan-1-one;especially preferred is1-[4-(2-hydroxy-ethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one.

The optional component (d) comprises at least one further diisocyanateand/or polyisocyanate which is different from the compound (a). Alsopossible in this context are the aforementioned diisocyanates, i.e.,compounds with a functionality of 2.

Suitable components (d) are, for example, aliphatic, aromatic, andcycloaliphatic diisocyanates and polyisocyanates having an NCOfunctionality of at least 2, preferably 2 to 5, and more preferably morethan 2 to 4.

Polyisocyanates contemplated include polyisocyanates containingisocyanurate groups, uretdione diisocyanates, polyisocyanates containingbiuret groups, polyisocyanates containing urethane groups or allophanategroups, polyisocyanates comprising oxadiazinetrione groups,uretonimine-modified polyisocyantes of linear or branched C₄-C₂₀alkylene diisocyanates, cycloaliphatic diisocyanates having a total of 6to 20 C atoms, or aromatic diisocyanates having a total of 8 to 20 Catoms, or mixtures thereof. Isocyanurates, biurets, and allophanates arepreferred, isocyanurates and allophanates are more preferred, andallophanates are very preferred.

The polyisocyanates are preferably polyisocyanates based on one or morediisocyanates having 4 to 20 C atoms. Examples of customarydiisocyanates are aliphatic diisocyanates such as tetramethylenediisocyanate, hexamethylene diisocyanate (1,6-diisocyanatohexane),octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylenediisocyanate, tetradecamethylene diisocyanate, derivatives of lysinediisocyanate, tetramethylxylylene diisocyanate, trimethylhexanediisocyanate or tetramethylhexane diisocyanate, cycloaliphaticdiisocyanates such as 1,4-, 1,3- or 1,2-diisocyanatocyclohexane, 4,4′-or 2,4′-di(isocyanatocyclohexyl)methane,1-isocyanato-3,3,5-trimethyl-5-(isocyanatomethyl)cyclohexane (isophoronediisocyanate), 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane or 2,4- or2,6-diisocyanato-1-methylcyclohexane, and also aromatic diisocyanatessuch as tolylene 2,4- or 2,6-diisocyanate and the isomer mixturesthereof, m- or p-xylylene diisocyanate, 2,4′- or4,4′-diisocyanato-diphenylmethane and the isomer mixtures thereof,phenylene 1,3- or 1,4-diisocyanate, 1-chlorophenylene 2,4-diisocyanate,naphthylene 1,5-diisocyanate, diphenylene 4,4′-diisocyanate,4,4′-diisocyanato-3,3′-dimethylbiphenyl, 3-methyldiphenylmethane4,4′-diisocyanate, tetramethylxylylene diisocyanate,1,4-diisocyanatobenzene or diphenyl ether 4,4′-diisocyanate.

Mixtures of the stated diisocyanates may also be present.

Preference is given to hexamethylene diisocyanate,1,3-bis(isocyanatomethyl)cyclohexane, isophorone diisocyanate, anddi(isocyanatocyclohexyl)methane; hexamethylene diisocyanate isparticularly preferred.

The polyisocyanates which can be used preferably have an isocyanategroup content (calculated as NCO, molecular weight=42) of 10% to 60% byweight, based on the diisocyanate and the polyisocyanate (mixture),preferably 15% to 60% by weight, and more preferably 20% to 55% byweight.

The polyisocyanates are preferably synthesized from aliphatic and/orcycloaliphatic polyisocyanates, examples being the abovementionedaliphatic or cycloaliphatic diisocyanates, respectively, or mixturesthereof.

Contemplated as component (e) are compounds which have at least twoisocyanate-reactive groups, examples being —OH, —SH, —NH₂ or —NHR², inwhich R² therein, independently of one another, may be hydrogen, methyl,ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl or tert-butyl.

Compounds (e) having precisely 2 isocyanate-reactive groups arepreferably diols having 2 to 20 carbon atoms, examples being ethyleneglycol, 1,2-propanediol, 1,3-propanediol, 1,1-dimethylethane-1,2-diol,2-butyl-2-ethyl-1,3-propanediol, 2-ethyl-1,3-propanediol,2-methyl-1,3-propanediol, neopentyl glycol, neopentyl glycolhydroxypivalate, 1,2-, 1,3- or 1,4-butanediol, 1,6-hexanediol,1,10-decanediol, bis(4-hydroxycyclohexane)isopropylidene,tetramethylcyclobutanediol, 1,2-, 1,3- or 1,4-cyclohexanediol,cyclooctanediol, norbornanediol, pinanediol, decalindiol,2-ethyl-1,3-hexanediol, 2,4-diethyloctane-1,3-diol, hydroquinone,bisphenol A, bisphenol F, bisphenol B, bisphenol S,2,2-bis(4-hydroxycyclohexyl)propane, 1,1-, 1,2-, 1,3-, and1,4-cyclohexanedimethanol, 1,2-, 1,3-, or 1,4-cyclohexanediol, polyTHFhaving a molar mass of between 162 and 2000, poly-1,2-propanediol orpoly-1,3-propanediol having a molar mass of between 134 and 1178 orpolyethylene glycol having a molar mass of between 106 and 2000, andalso aliphatic diamines, such as methylene- andisopropylidene-bis(cyclohexylamine), piperazine, 1,2-, 1,3- or1,4-diaminocyclohexane, 1,2-, 1,3-, or 1,4-cyclohexanebis(methylamine),etc., dithiols or polyfunctional alcohols, secondary or primary aminoalcohols, such as ethanolamine, monopropanolamine, etc. or thioalcohols, such as thioethylene glycol.

Particularly suitable here are the cycloaliphatic diols, such as, forexample, bis(4-hydroxycyclohexane)isopropylidene,tetramethylcyclobutanediol, 1,2-, 1,3-, or 1,4-cyclohexanediol, 1,1-,1,2-, 1,3-, and 1,4-cyclohexanedimethanol, cyclooctanediol ornorbornanediol.

Further compounds (e) may be compounds having at least threeisocyanate-reactive groups.

For example, these components may have 3 to 6, preferably 3 to 5, morepreferably 3 to 4, and very preferably 3 isocyanate-reactive groups.

The molecular weight of these components is generally not more than 2000g/mol, preferably not more than 1500 g/mol, more preferably not morethan 1000 g/mol, and very preferably not more than 500 g/mol.

These are preferably polyols having 2 to 20 carbon atoms, examples beingtrimethylolbutane, trimethylolpropane, trimethylolethane,pentaerythritol, glycerol, ditrimethylolpropane, dipentaerythritol,sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol(ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol,and isomalt; particularly preferred are trimethylolpropane,pentaerythritol, and glycerol; and especially preferred istrimethylolpropane.

Optional components (f) are those having optionally at least onecompound with precisely one isocyanate-reactive group. In one preferredembodiment there is at least one component (f) present.

In that case the components are preferably monools, more preferablyalkanols, and very preferably alkanols having 1 to 20, preferably 1 to12, more preferably 1 to 6, very preferably 1 to 4, and moreparticularly 1 to 2 carbon atoms.

Examples thereof are methanol, ethanol, isopropanol, n-propanol,n-butanol, isobutanol, sec-butanol, tert-butanol, n-hexanol, n-heptanol,n-octanol, n-decanol, isodecanol isomer mixtures, undecanol, n-dodecanol(lauryl alcohol), isotridecanol isomer mixtures, n-tridecanol,tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol,nonadecanol, eicosanol, 2-ethylhexanol, cyclopentanol, cyclohexanol,cyclooctanol, cyclododecanol, ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, diethylene glycol, 1,3-propanediol monomethylether; preferred are methanol, ethanol, isopropanol, n-propanol,n-butanol, tert-butanol, n-hexanol, 2-ethyl-hexanol, cyclopentanol,cyclohexanol, and cyclododecanol; particularly preferred are methanol,ethanol, isopropanol, n-propanol, n-butanol, and tert-butanol;especially preferred are n-propanol and ethanol; and ethanol moreparticularly.

In one less preferred but possible embodiment it is possible for themonools to be the stated cycloaliphatic alcohols, preferablycyclopentanol or cyclohexanol, more preferably cyclohexanol.

In a further preferred embodiment the monools may be the statedaliphatic alcohols having 6 to 20 carbon atoms, more preferably thosehaving 8 to 20 carbon atoms, very preferably those having 10 to 20carbon atoms.

In one particularly preferred embodiment the monools are the statedaliphatic alcohols, very preferably those having 1 to 4 carbon atoms,more particularly ethanol.

In one alternative further particularly preferred embodiment the monoolsare alkoxylated aliphatic alcohols of the formula

R⁹—O—[—Z_(i)—]_(q)—H

in whichR⁹ is an alkyl radical having 1 to 20 carbon atoms, preferably 10 to 20carbon atoms,q is a positive integer from 1 to 15, preferably 1 to 10, andZ_(i) for i=1 to q independently of one another may be selected from thegroup of —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, —CH(CH₃)—CH₂—O—, —CH₂—C(CH₃)₂—O—,—C(CH₃)₂—CH₂—O—, —CH₂—CHVin-O—, —CHVin-CH₂—O—, —CH₂—CHPh-O—, and—CHPh-CH₂—O—, preferably from the group of —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—,and —CH(CH₃)—CH₂—O—, and more preferably —CH₂—CH₂—O—.

When alkoxylated aliphatic alcohols of this kind are used as component(f) in the polyurethanes (A) of the invention, the polyurethanes (A)thus obtainable, in addition to their otherwise positive properties,exhibit improved dispersion of pigments in the inks and printing-inks ofthe invention, allowing an increased color density in the print.

The polyurethanes which can be used in accordance with the invention areobtained by reacting the components (a), (b), and (c), and also,optionally (d) and/or (e) and/or (f), with one another.

In this case the molar composition (a):(b):(c):(d):(e):(f) per mole ofreactive isocyanate groups in (a) and (d) together is generally asfollows:

-   (b) 1-50, preferably 5-40, more preferably 10-37.5, and more    particularly 15-33 mol % of isocyanate-reactive groups,-   (c) 1-50, preferably 5-40, more preferably 10-37.5, and more    particularly 15-33 mol % of isocyanate-reactive groups,-   (e) 0-50, preferably 0-30, more preferably 0-25, and more    particularly 0-20, and especially 0 mol % of isocyanate-reactive    groups,-   (f) 0-5, preferably 0.1-3, and more preferably 0.2-2 mol % of    isocyanate-reactive groups,    with the proviso that the sum total of the isocyanate-reactive    groups corresponds to the number of isocyanate groups in (a) and (d)    where the latter have not been consumed by reaction with other    isocyanate groups to form oligomeric polyisocyanates, as for example    to form dimers or trimers. The fraction of isocyanate groups    from (d) as a proportion of the sum total of the isocyanate groups    in (a) and (d) may for example be up to 50%, preferably up to 25%,    more preferably up to 10%, and very preferably 0—i.e., there is no    compound (d) present.

In the preferred embodiment in which the polyurethane (A) of theinvention is prepared using a polyisocyanate of the formula (I)containing allophanate groups, this polyisocyanate already being anadduct of components (a) and (b), the molar composition per reactiveisocyanate groups in the compound of the formula (I) is as follows:

-   (b) 0 to 30 mol %, preferably 0 to 20, more preferably 0 to 10, and    very preferably 0 mol % of isocyanate-reactive groups,-   (c) 50 to 100 mol %, preferably 60 to 90, and more preferably 60 to    80 mol % of isocyanate-reactive groups,-   (d) 0 to 30 mol %, preferably 0 to 20, more preferably 0 to 10, and    very preferably 0 mol % of isocyanate groups,-   (e) 0 to 20 mol %, preferably 0 to 10, more preferably 0 to 50, and    very preferably 0 mol % of isocyanate-reactive groups,-   (f) 0-20, preferably 0.1-20, and more preferably 0.2-20 mol % of    isocyanate-reactive groups,    with the proviso that the sum total of isocyanate-reactive groups    corresponds to the sum total of isocyanate groups.

The formation of the adduct of compound containing isocyanate groups andthe compound which contains groups that are reactive toward isocyanategroups is generally accomplished by mixing the components in any order,optionally at elevated temperature.

It is preferred here to add the compound containing groups that arereactive toward isocyanate groups to the compound containing isocyanategroups, preferably in two or more steps.

With particular preference, the compound (a), and also optionally (d),containing isocyanate groups is introduced initially and the compoundswhich contain isocyanate-reactive groups are added. More particularly,the compound (a) containing isocyanate groups is introduced initially,and then (b) and/or (c) preferably (b), are/is added. After that anydesired further components may be added.

Generally speaking, the reaction is carried out at temperatures between5 and 100° C., preferably between 20 to 90° C., and more preferablybetween 40 and 80° C., and more particularly between 60 and 80° C.

The process of the invention is carried out in the presence of less than1000 ppm by weight, preferably less than 500, more preferably less than250 and very preferably less than 100 ppm by weight of a bismuth-, zinc-and/or titanium-containing compound, preferably of a bismuth- and/ortitanium-containing compound, and more preferably of abismuth-containing compound.

Zinc and bismuth compounds contemplated are those in which the followinganions are used: F⁻, Cl⁻, ClO⁻, ClO₃ ⁻, ClO₄ ⁻, Br⁻, I⁻, IO₃ ⁻, CN⁻,OCN⁻, NO₂ ⁻, NO₃ ⁻, HCO₃ ⁻, CO₃ ²⁻, S²⁻, SH⁻, HSO₃ ⁻, SO₃ ²⁻, HSO₄ ⁻,SO₄ ²⁻, S₂O₂ ²⁻, S₂O₄ ²⁻, S₂O₅ ²⁻, S₂O₆ ²⁻, S₂O₇ ²⁻, S₂O₈ ²⁻, H₂PO₂ ⁻,H₂PO₄ ⁻, HPO₄ ²⁻, PO₄ ³⁻, P₂O₇ ⁴⁻, (OC_(n)H_(2n+1))⁻,(C_(n)H_(2n−1)O₂)⁻, (C_(n)H_(2n−3)O₂)⁻, and (C_(n+1)H_(2n−1)O₄)²⁻, wheren stands for the numbers 1 to 20.

Preference here is given to the carboxylates in which the anion conformsto the formulae (C_(n)H_(2n−1)O₂)⁻ and also (C_(n+1)H_(2n−2)O₄)²⁻ with nbeing 1 to 20. Particularly preferred salts have monocarboxylate anionsof the general formula (C_(n)H_(2n−1)O₂)⁻ where n stands for the numbers1 to 20. Particularly noteworthy in this context are formate, acetate,propionate, hexanoate, neodecanoate, and 2-ethylhexanoate.

Among the zinc catalysts the zinc carboxylates are preferred, morepreferably those of carboxylates which have at least six carbon atoms,very preferably at least eight carbon atoms, more particularly zinc(II)diacetate or zinc(II) dioctoate or zinc(II) neodecanoate. Commercialcatalysts are, for example, Borchi® Kat 22 from OMG Borchers GmbH,Langenfeld, Germany.

Among the bismuth catalysts the bismuth carboxylates are preferred, morepreferably those of carboxylates which have at least six carbon atoms,more particularly bismuth octoates, ethylhexanoates, neodecanoates, orpivalates; examples are K-KAT 348, XC-B221; XC-C227, XC 8203, and XK-601from King Industries, TIB KAT 716, 716LA, 716XLA, 718, 720, and 789 fromTIB Chemicals, and those from Shepherd Lausanne, and also, for example,Borchi® Kat 24; 315; 320 from OMG Borchers GmbH, Langenfeld, Germany.

The catalysts may also comprise mixtures of different metals, as forexample in Borchi® Kat 0245 from OMG Borchers GmbH, Langenfeld, Germany.

Among the titanium compounds the titanium tetra-alcoholates Ti(OR)₄ arepreferred, more preferably those of alcohols ROH having 1 to 8 carbonatoms, examples being methanol, ethanol, isopropanol, n-propanol,n-butanol, isobutanol, sec-butanol, tert-butanol, n-hexanol, n-heptanol,n-octanol; preferably methanol, ethanol, isopropanol, n-propanol,n-butanol, tert-butanol; more preferably isopropanol and n-butanol.

In the process of the invention operation takes place under water-freeconditions. Water-free here means that the water content in the reactionsystem is not more than 5% by weight, preferably not more than 3% byweight, and more preferably not more than 1% by weight, very preferablynot more than 0.75%, and more particularly not more than 0.5% by weight.If operation is not water-free, the risk exists of water reacting withthe free isocyanate groups under the reaction conditions, and of theamino groups which form causing secondary reaction, as for example aMichael addition to (meth)acrylate groups, or reaction with further freeisocyanate groups to form low-solubility biurets.

The reaction is carried out preferably in the presence of at least oneoxygen-containing gas, examples being air or air/nitrogen mixtures, ormixtures of oxygen or an oxygen-containing gas with a gas which is inertunder the reaction conditions, such mixtures having an oxygen content ofbelow 15%, preferably below 12%, more preferably below 10%, verypreferably below 8%, and more particularly below 6% by volume.

In one preferred embodiment the reaction mixture is admixed with up to1000 ppm by weight of at least one process stabilizer. Preferred processstabilizers are phenothiazine, 2,2,6,6-tetramethylpiperidine-N-oxyl, andalso quinone methides.

In one preferred embodiment the reaction of the compound (a) containingisocyanate groups, or of the reaction product of (a) and (b), with thecompound (c) is carried out such that the compound containing isocyanategroups is used in an excess of NCO groups, relative to theisocyanate-reactive groups in (c), of at least 20 mol %. A consequenceof this is that the compounds (c) are incorporated substantiallycompletely by reaction. The excess of isocyanate groups can be reactedsubsequently with further compound (b) and/or compound (f), preferablywith compound (f).

The reaction can also be carried out in the presence of an inertsolvent, an example being acetone, isobutyl methyl ketone, toluene,xylene, butyl acetate, methoxypropyl acetate, or ethoxyethyl acetate.Preferably, however, the reaction is carried out in the absence of asolvent.

In one preferred embodiment the reaction of (a) with (b) and/or (c),preferably (a) and (b), is carried out under allophanatizationconditions. By these are meant reaction conditions under whichallophanate groups are formed at least in part, preferably reactionconditions under which, among various competing reactions of theisocyanate groups, more isocyanate groups are consumed by reaction toform allophanate groups than to form other reaction products.

In a further preferred embodiment, compounds used are of the kinddescribed in WO 00/39183, page 4, line 3 to page 10, line 19, thedisclosure content of which is hereby part of the present specification.Particularly preferred among these are those compounds which assynthesis components have at least one (cyclo)aliphatic isocyanatecontaining allophanate groups, and at least one hydroxylalkyl(meth)acrylate—very preferably the products 1 to 9 in table 1 on page 24of WO 00/39183. With very particular preference the compounds inquestion are those polyisocyanates of the formula (I) described above.

Further provided with the present invention are formulations ofincorporable photoinitiators, consisting of at least one polyurethane Acomprising as synthesis components

-   (a) at least one organic aliphatic, aromatic or cycloaliphatic    diisocyanate or polyisocyanate having a functionality of more than    2,-   (b) at least one compound having in each case at least one    isocyanate-reactive group and at least one radically polymerizable    unsaturated group,-   (c) at least one photoinitiator having at least one    isocyanate-reactive group,-   (d) optionally at least one further diisocyanate and/or    polyisocyanate, which is different from the compound (a),-   (e) optionally at least one compound having at least two    isocyanate-reactive groups,-   (f) optionally at least one compound having precisely one    isocyanate-reactive group, optionally at least one polyfunctional    polymerizable compound (B),    and also 0.5% to 4% by weight of water, based on the amount of    polyurethane (A).

The amount of water is preferably at least 0.75% by weight, morepreferably at least 1% by weight, very preferably at least 1.25% byweight and more particularly at least 1.5% by weight, based on theamount of polyurethane (A).

The amount of water is preferably up to 3.5% by weight, more preferablyup to 3% by weight, based on the amount of polyurethane (A).

These formulations are generally stable in storage and do not undergoseparation.

An advantage of these formulations is that by admixing of the statedamount of water it is possible to reduce the viscosity of thepolyurethane (A). Generally speaking the viscosity, measured to DIN ENISO 3219 (shear rate D, 100 s⁻¹) at 23° C., is not more than 400 Pas,and so the formulation is fluid. The viscosity is preferably less than300, more preferably less than 250 Pas, and very preferably less than200 Pas.

The formulation may take the form of a solution or dispersion,preferably a solution of water in the polyurethane (A). For mixing, theamount of water is introduced, optionally in portions, into thepolyurethane (A), with introduction of energy. It is also possible,however, for the polyurethane (A) to be added to water.

Mixing may take place, for example, by stirring, static mixers, orultrasound; preferably by stirring.

The polyurethanes (A) and the formulations of incorporablephotoinitiators of the invention can be used preferably in inks,printing-inks, and print varnishes of the invention.

The present invention further provides inks, printing-inks and printvarnishes comprising

at least one polyurethane A comprising as synthesis components

-   (a) at least one organic aliphatic, aromatic or cycloaliphatic    diisocyanate or polyisocyanate having a functionality of more than    2,-   (b) at least one compound having in each case at least one    isocyanate-reactive group and at least one radically polymerizable    unsaturated group,-   (c) at least one photoinitiator having at least one    isocyanate-reactive group,-   (d) optionally at least one further diisocyanate and/or    polyisocyanate, which is different from the compound (a),-   (e) optionally at least one compound having at least two    isocyanate-reactive groups,-   (f) optionally at least one compound having precisely one    isocyanate-reactive group,    and also, in addition to the polyurethane (A),    0.5 to 4% by weight of water, based on the amount of polyurethane    (A),    optionally at least one pigment,    at least one polyfunctional polymerizable compound (B),    optionally at least one further photoinitiator, and also    optionally additives typical of printing-inks.

The print varnishes of the invention contain no pigments.

The at least one further photoinitiator is preferably present in thecase of pigmented printing-inks and in the case of print varnishes.

The term “printing-ink” is used in this specification as a collectivedesignation for colorant-containing preparations with a variety ofconsistencies, these preparations being applied exclusively by means ofa printing form to a print-receiving medium, where they are fixed in theform of a colored film (print) (CEPE definition).

The term “ink” in this specification is used exclusively for coloredliquids for ink-jet liquid and also for liquid toners forelectrophotographic printing processes.

The inks, printing-inks, and print varnishes of the invention can beused for printing a variety of substrates, preferably polyamides,polyethylene, polypropylene, polyesters, polyethylene terephthalate,polystyrene, paper, paperboard, cardboard, plastics-coated paper,plastics-coated paperboard or plastics-coated cardboard, aluminum, andaluminum-coated polymeric films, preferably polyethylene, polypropylene,and polyesters, and also paper and cardboard.

Where paper, paperboard or cardboard is plastics-coated, the plastic inquestion preferably comprises polyolefins, more preferably polyethyleneor polypropylene.

The substrates thus printed are especially suitable as packagingmaterials for food and drink, cosmetics, and pharmaceuticals.

The polyurethanes (A) of the invention may be used as sole binder or,preferably, in combination with at least one further radicallypolymerizable compound.

Radically polymerizable groups are, for example, preferably(meth)acrylate groups and more preferably acrylate groups.

The radically polymerizable compounds (B) are preferably polyfunctional(compound having more than one radically polymerizable double bond)polymerizable compounds.

(Meth)acrylic acid stands in this specification for methacrylic acid andacrylic acid, preferably for acrylic acid.

Multifunctional polymerizable compounds are preferably multifunctional(meth)acrylates which carry at least 2, preferably 2-10, more preferably3-6, and very preferably 3-4 (meth)acrylate groups, preferably acrylategroups.

Examples of multifunctional polymerizable compounds are ethylene glycoldiacrylate, 1,2-propanediol diacrylate, 1,3-propanediol diacrylate,1,4-butanediol diacrylate, 1,3-butanediol diacrylate, 1,5-pentanedioldiacrylate, 1,6-hexanediol diacrylate, 1,8-octanediol diacrylate,neopentyl glycol diacrylate, 1,1-, 1,2-, 1,3-, and1,4-cyclohexanedimethanol diacrylate, 1,2-, 1,3- or 1,4-cyclohexanedioldiacrylate, dipropylene glycol diacrylate trimethylolpropanetriacrylate, ditrimethylolpropane tipropylene glycol diacrylate penta-or hexaacrylate, pentaerythritol tri- or tetraacrylate, glycerol di- ortriacrylate, and also di- and polyacrylates of sugar alcohols, such assorbitol, mannitol, diglycerol, threitol, erythritol, adonitol(ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitolor isomalt, or of polyester polyols, polyetherols, poly THF having amolar mass of between 162 and 2000, poly-1,3-propanediol having a molarmass of between 134 and 1178, polyethylene glycol having a molar mass ofbetween 106 and 898, and also epoxy tetraacrylate dipentaerythritol(meth)acrylates, polyester (meth)acrylates, polyether (meth)acrylates,urethane (meth)acrylates or polycarbonate (meth)acrylates, whichoptionally may also have been modified with one or more amines.

Further examples are (meth)acrylates of compounds of formula (VIIIa) to(VIIId)

in whichR⁷ and R⁸ independently of one another are hydrogen or are C₁-C₁₈ alkylwhich is optionally substituted by aryl, alkyl, aryloxy, alkyloxy,heteroatoms and/or heterocycles,k, l, m, and q independently of one another are each an integer from 1to 10, preferably 1 to 5, and more preferably 1 to 3, andeach X_(i) for i=1 to k, 1 to l, 1 to m, and 1 to q can be selectedindependently of one another from the group —CH₂—CH₂—O—,—CH₂—CH(CH₃)—O—, —CH(CH₃)—CH₂—O—, —CH₂—C(CH₃)₂—O—, —C(CH₃)₂—CH₂—O—,—CH₂—CHVin-O—, —CHVin-CH₂—O—, —CH₂—CHPh-O—, and —CHPh-CH₂—O—, preferablyfrom the group —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, and —CH(CH₃)—CH₂—O—, andmore preferably —CH₂—CH₂—O—,in which Ph is phenyl and Vin is vinyl.C₁-C₁₈ alkyl therein, optionally substituted by aryl, alkyl, aryloxy,alkyloxy, heteroatoms and/or heterocycles, is for example methyl, ethyl,propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl,heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, decyl, dodecyl,tetradecyl, hexadecyl, octadecyl, 1,1-dimethylpropyl, 1,1-dimethylbutyl,1,1,3,3-tetramethylbutyl, preferably methyl, ethyl or n-propyl, morepreferably methyl or ethyl.

These are preferably (meth)acrylates of singly to vigintuply and morepreferably triply to decuply ethoxylated, propoxylated or mixedlyethoxylated and propoxylated, and in particular exclusively ethoxylated,neopentyl glycol, trimethylolpropane, trimethyl-olethane orpentaerythritol.

Preferred multifunctional polymerizable compounds are 1,2-propanedioldiacrylate, 1,3-propanediol diacrylate, dipropylene glycol diacrylate,tripropylene glycol diacrylate, trimethylolpropane triacrylate,ditrimethylol tetracrylate, and dipentaerythritol hexaacrylate,polyester polyol acrylates, polyetherol acrylates, and triacrylate ofsingly to vigintuply alkoxylated, more preferably singly to vigintuplyethoxylated trimethylolpropane, singly to vigintuply propoxylatedglycerol or singly to vigintuply ethoxylated and/or propoxylatedpentaerythritol.

In one preferred embodiment, epoxy (meth)acrylates are used asmultifunctional polymerizable compounds in print varnishes.

Especially preferred multifunctional polymerizable compounds aretrimethylolpropane triacrylate and triacrylate of singly to vigintuplyethoxylated trimethylolpropane, triacrylate of singly to vigintuplypropoxylated glycerol or tetraacrylate of singly to vigintuplyethoxylated and/or propoxylated pentaerythritol.

Further constituents may also be polyalcohols with full or partialesterification with (meth)acrylic acid.

Examples of such polyalcohols are at least divalent polyols,polyetherols or polyesterols, or polyacrylate polyols, having an averageOH functionality of at least 2, preferably at least 3, more preferablyat least 4, and very preferably 4 to 20.

Polyetherols, in addition to the alkoxylated polyols, may also bepolyethylene glycol having a molar mass of between 106 and 2000,polypropylene glycol having a molar weight of between 134 and 2000,polyTHF having a molar weight of between 162 and 2000, orpoly-1,3-propanediol having a molar weight of between 134 and 400.

Polyester polyols are known for example from Ullmanns Encyklopädie dertechnischen Chemie, 4th edition, volume 19, pp. 62 to 65. Preference isgiven to using polyester polyols obtained by reacting dihydric alcoholswith dibasic carboxylic acids. In lieu of the free polycarboxylic acidsit is also possible to use the corresponding polycarboxylic anhydridesor corresponding polycarboxylic esters of lower alcohols or mixturesthereof to prepare the polyester polyols. The polycarboxylic acids maybe aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic andmay optionally be substituted, by halogen atoms for example, and/orunsaturated. Examples thereof that may be mentioned include thefollowing:

oxalic acid, maleic acid, fumaric acid, succinic acid, glutaric acid,adipic acid, sebacic acid, dodecanedioic acid, o-phthalic acid,isophthalic acid, terephthalic acid, trimellitic acid, azelaic acid,1,4-cyclohexanedicarboxylic acid or tetrahydrophthalic acid, subericacid, azelaic acid, phthalic anhydride, tetrahydrophthalic anhydride,hexahydrophthalic anhydride, tetrachlorophthalic anhydride,endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleicanhydride, dimeric fatty acids, their isomers and hydrogenationproducts, and also esterifiable derivatives, such as anhydrides ordialkyl esters, C₁-C₄-alkyl esters for example, preferably methyl, ethylor n-butyl esters, of said acids are used. Preference is given todicarboxylic acids of the general formula HOOC—(CH₂)_(y)—COOH, y being anumber from 1 to 20, preferably an even number from 2 to 20; morepreferably succinic acid, adipic acid, sebacic acid, anddodecanedicarboxylic acid.

Suitable polyhydric alcohols for preparing the polyesterols include1,2-propanediol, ethylene glycol, 2,2-dimethyl-1,2-ethanediol,1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol,3-methylpentane-1,5-diol, 2-ethylhexane-1,3-diol,2,4-diethyloctane-1,3-diol, 1,6-hexanediol, polyethylene glycol having amolar weight between 106 and 2000, polypropylene glycol having a molarweight between 134 and 2000, polyTHF having a molar mass between 162 and2000, poly-1,3-propanediol having a molar weight between 134 and 400,neopentyl glycol, neopentyl glycol hydroxypivalate,2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol,2,2-bis(4-hydroxycyclohexyl)propane, 1,1-, 1,2-, 1,3-, and1,4-cyclohexanedimethanol, 1,2-, 1,3- or 1,4-cyclohexanediol,trimethylolbutane, trimethylolpropane, trimethylolethane, neopentylglycol, pentaerythritol, glycerol, ditrimethylolpropane,dipentaerythritol, sorbitol, mannitol, diglycerol, threitol, erythritol,adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol),maltitol or isomalt, which optionally may have been alkoxylated asdescribed above.

Preferred alcohols are those of the general formula HO—(CH₂)_(x)—OH, xbeing a number from 1 to 20, preferably an even number from 2 to 20.Preference is given to ethylene glycol, butane-1,4-diol,hexane-1,6-diol, octane-1,8-diol, and dodecane-1,12-diol. Preference isfurther given to neopentyl glycol.

Also suitable are lactone-based polyesterdiols, which are homopolymersor copolymers of lactones, preferably hydroxyl-terminated adducts oflactones with suitable difunctional starter molecules. Suitable lactonesinclude, preferably, those deriving from compounds of the generalformula HO—(CH₂)_(z)—COOH, z being a number from 1 to 20 and it beingpossible for an H atom of a methylene unit also to have been substitutedby a C₁ to C₄ alkyl radical. Examples are ε-caprolactone,β-propiolactone, gamma-butyrolactone and/or methyl-ε-caprolactone,4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid or pivalolactone, andmixtures thereof. Examples of suitable starter components are the lowmolecular mass dihydric alcohols specified above as a synthesiscomponent for the polyester polyols. The corresponding polymers ofε-caprolactone are particularly preferred. Lower polyesterdiols orpolyetherdiols as well can be used as starters for preparing the lactonepolymers. In lieu of the polymers of lactones it is also possible to usethe corresponding, chemically equivalent polycondensates of thehydroxycarboxylic acids corresponding to the lactones.

Also suitable, furthermore, are polycarbonatediols, such as may beobtained, for example, by reacting phosgene with an excess of the lowmolecular weight alcohols specified as synthesis components for thepolyester polyols.

The multifunctional polymerizable compound, may also comprise urethane(meth)acrylates, epoxy (meth)acrylates or carbonate (meth)acrylates.

Urethane (meth)acrylates are obtainable for example by reactingpolyisocyanates with hydroxyalkyl (meth)acrylates and optionally chainextenders such as diols, polyols, diamines, polyamines, dithiols orpolythiols. Urethane (meth)acrylates which can be dispersed in waterwithout addition of emulsifiers additionally comprise ionic and/ornonionic hydrophilic groups, which are introduced into the urethane bymeans of synthesis components such as hydroxycarboxylic acids, forexample.

Urethane (meth)acrylates of this kind comprise as synthesis componentssubstantially:

-   (1) at least one organic aliphatic, aromatic or cycloaliphatic di-    or polyisocyanate,-   (2) at least one compound having at least one isocyanate-reactive    group and at least one radically polymerizable unsaturated group,    and-   (3) optionally, at least one compound having at least two    isocyanate-reactive groups.

Possible useful components (1), (2), and (3) may be the same as thosedescribed above as synthesis components (a), (b), and (e) for thepolyurethanes of the invention.

The urethane (meth)acrylates preferably have a number-average molarweight M_(n) of 500 to 20 000, in particular of 500 to 10 000 and morepreferably 600 to 3000 g/mol (determined by gel permeationchromatography using tetrahydrofuran and polystyrene as standard).

The urethane (meth)acrylates preferably have a (meth)acrylic groupcontent of 1 to 5, more preferably of 2 to 4, mol per 1000 g of urethane(meth)acrylate.

Epoxy (meth)acrylates are obtainable by reacting epoxides with(meth)acrylic acid. Examples of suitable epoxides include epoxidizedolefins, aromatic glycidyl ethers or aliphatic glycidyl ethers,preferably those of aromatic or aliphatic glycidyl ethers.

Examples of possible epoxidized olefins include ethylene oxide,propylene oxide, iso-butylene oxide, 1-butene oxide, 2-butene oxide,vinyloxirane, styrene oxide or epichlorohydrin, preference being givento ethylene oxide, propylene oxide, isobutylene oxide, vinyloxirane,styrene oxide or epichlorohydrin, particular preference to ethyleneoxide, propylene oxide or epichlorohydrin, and very particularpreference to ethylene oxide and epichlorohydrin.

Aromatic glycidyl ethers are, for example, bisphenol A diglycidyl ether,bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, bisphenol Sdiglycidyl ether, hydroquinone diglycidyl ether, alkylation products ofphenol/dicyclopentadiene, e.g.,2,5-bis[(2,3-epoxypropoxy)phenyl]octahydro-4,7-methano-5H-indene (CASNo. [13446-85-0]), tris[4-(2,3-epoxypropoxy)phenyl]methane isomers (CASNo. [66072-39-7]), phenol-based epoxy novolaks (CAS No. [9003-35-4]),and cresol-based epoxy novolaks (CAS No. [37382-79-9]).

Examples of aliphatic glycidyl ethers include 1,4-butanediol diglycidylether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidylether, pentaerythritol tetraglycidyl ether,1,1,2,2-tetrakis[4-(2,3-epoxypropoxy)phenyl]ethane (CAS No.[27043-37-4]), diglycidyl ether of polypropylene glycol(α,ω-bis(2,3-epoxypropoxy)poly(oxypropylene), CAS No. [16096-30-3]) andof hydrogenated bisphenol A(2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane, CAS No. [13410-58-7]).

The epoxy (meth)acrylates preferably have a number-average molar weightM_(n) of 200 to 20 000, more preferably of 200 to 10 000 g/mol, and verypreferably of 250 to 3000 g/mol; the amount of (meth)acrylic groups ispreferably 1 to 5, more preferably 2 to 4, per 1000 g of epoxy(meth)acrylate (determined by gel permeation chromatography usingpolystyrene as standard and tetrahydrofuran as eluent).

Carbonate (meth)acrylates comprise on average preferably 1 to 5,especially 2 to 4, more preferably 2 to 3 (meth)acrylic groups, and verypreferably 2 (meth)acrylic groups.

The number-average molecular weight M_(n) of the carbonate(meth)acrylates is preferably less than 3000 g/mol, more preferably lessthan 1500 g/mol, very preferably less than 800 g/mol (determined by gelpermeation chromatography using polystyrene as standard, tetrahydrofuranas solvent).

The carbonate (meth)acrylates are obtainable in a simple manner bytransesterifying carbonic esters with polyhydric, preferably dihydric,alcohols (diols, hexanediol for example) and subsequently esterifyingthe free OH groups with (meth)acrylic acid, or else bytransesterification with (meth)acrylic esters, as described for examplein EP-A 92 269. They are also obtainable by reacting phosgene, ureaderivatives with polyhydric, e.g., dihydric, alcohols.

Also conceivable are (meth)acrylates of polycarbonate polyols, such asthe reaction product of one of the aforementioned diols or polyols and acarbonic ester and also a hydroxyl-containing (meth)acrylate.

Examples of suitable carbonic esters include ethylene carbonate, 1,2- or1,3-propylene carbonate, dimethyl carbonate, diethyl carbonate ordibutyl carbonate.

Examples of suitable hydroxyl-containing (meth)acrylates are2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate,1,4-butanediol mono(meth)acrylate, neopentyl glycol mono(meth)acrylate,glyceryl mono- and di(meth)acrylate, trimethylolpropane mono- anddi(meth)acrylate, and pentaerythritol mono-, di-, and tri(meth)acrylate.

Particularly preferred carbonate (meth)acrylates are those of theformula:

in which R is H or CH₃, X is a C₂-C₁₈ alkylene group, and n is aninteger from 1 to 5, preferably 1 to 3.R is preferably H and X is preferably C₂ to C₁₀ alkylene, examples being1,2-ethylene, 1,2-propylene, 1,3-propylene, 1,4-butylene, and1,6-hexylene, more preferably C₄ to C₈ alkylene. With very particularpreference X is C₆ alkylene.

The carbonate (meth)acrylates are preferably aliphatic carbonate(meth)acrylates.

Among the multifunctional polymerizable compounds, urethane(meth)acrylates are particularly preferred.

It may be useful to add photoinitiator—preferably photoinitiator with adifferent absorption maximum from component (c)—, in addition to thepolyurethane (A), to the inks, printing-inks, and print varnishes of theinvention.

Photoinitiators may be, for example, photoinitiators known to theskilled person, examples being those specified in “Advances in PolymerScience”, Volume 14, Springer Berlin 1974 or in K. K. Dietliker,Chemistry and Technology of UV and EB Formulation for Coatings, Inks andPaints, Volume 3; Photoinitiators for Free Radical and CationicPolymerization, P. K. T. Oldring (Eds), SITA Technology Ltd, London.

Suitability is possessed, for example, by mono- or bisacylphosphineoxides, as described for example in EP-A 7 508, EP-A 57 474, DE-A 196 18720, EP-A 495 751 or EP-A 615 980, examples being2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin® TPO from BASFSE), ethyl 2,4,6-trimethylbenzoylphenylphosphinate (Lucirin® TPO L fromBASF SE), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure®819 from BASF SE), benzophenones, hydroxyacetophenones, phenylglyoxylicacid and its derivatives, or mixtures of these photoinitiators. Examplesthat may be mentioned include benzophenone, acetophenone,acetonaphthoquinone, methyl ethyl ketone, valerophenone, hexanophenone,α-phenylbutyrophenone, p-morpholinopropiophenone, dibenzosuberone,4-morpholinobenzophenone, 4-morpholinodeoxybenzoin, p-diacetylbenzene,4-aminobenzophenone, 4′-methoxyacetophenone, β-methylanthraquinone,tert-butylanthraquinone, anthraquinonecarboxylic esters, benzaldehyde,α-tetralone, 9-acetylphenanthrene, 2-acetylphenanthrene,10-thioxanthone, 3-acetylphenanthrene, 3-acetylindole, 9-fluorenone,1-indanone, 1,3,4-triacetylbenzene, thioxanthen-9-one, xanthen-9-one,2,4-dimethylthioxanthone, 2,4-diethylthioxanthone,2,4-diisopropylthioxanthone, 2,4-dichlorothioxanthone, benzoin, benzoinisobutyl ether, chloroxanthenone, benzoin tetrahydropyranyl ether,benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoinisopropyl ether, 7H-benzoin methyl ether, benz[de]anthracen-7-one,1-naph-thaldehyde, 4,4′-bis(dimethylamino)benzophenone,4-phenylbenzophenone, 4-chloro-benzophenone, Michler's ketone,1-acetonaphthone, 2-acetonaphthone, 1-benzoyl-cyclohexan-1-ol,2-hydroxy-2,2-dimethylacetophenone, 2,2-dimethoxy-2-phenylaceto-phenone,2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone,1-hydroxyacetophenone, acetophenone dimethyl ketal,o-methoxybenzophenone,2-hydroxy-1-[4-[[4-(2-hydroxy-2-methylpropanoyl)phenyl]methyl]phenyl]-2-methylpropan-1-one,2-benzyl-2-dimethylamino-4′-morpholinobutyrophenone,2-(dimethylamino)-1-(4-morpholinophenyl)-2-(p-tolylmethyl)butan-1-one,2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one,triphenylphosphine, tri-o-tolylphosphine, benz[a]anthracene-7,12-dione,2,2-diethoxyacetophenone, benzil ketals, such as benzil dimethyl ketal,anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone,2-tert-butylanthraquinone, 1-chloroanthraquinone, and2-amylanthraquinone, and 2,3-butanedione.

Likewise conceivable as photoinitiators are polymeric photoinitiatorssuch as, for example, the diester of carboxymethoxybenzophenone withpolytetramethylene glycols of different molar weights, preferably 200 to250 g/mol (CAS 515136-48-8), and also CAS 1246194-73-9, CAS 813452-37-8,CAS 71512-90-8, CAS 886463-10-1, or further polymeric benzophenonederivatives, of the kind available commercially, for example, under thetrade name Omnipol® BP from IGM Resins B.V., Waalwijk, The Netherlands,or Genopol® BP1 from Rahn AG, Switzerland. Also conceivable,furthermore, are polymeric thioxanthones, examples being the diesters ofcarboxymethoxythioxanthones with polytetramethylene glycols of variousmolar weights, of the kind available commercially, for example, underthe trade name Omnipol® TX from IGM Resins B.V., Waalwijk, TheNetherlands. Also conceivable, furthermore, are polymeric α-aminoketones, examples being the diester of carboxyethoxythioxanthones withpolyethylene glycols of various molar weights, of the kind availablecommercially, for example, under the trade name Omnipol® 910 or Omnipol®9210 from IGM Resins B.V., Waalwijk, The Netherlands.

One preferred embodiment uses, as photoinitiators, silsesquioxanecompounds having at least one initiating group, of the kind described inWO 2010/063612 A1, particularly from page 2, line 21 to page 43, line 9therein, hereby incorporated by reference as part of the presentdisclosure content, preferably from page 2, line 21 to page 30, line 5,and also the compounds described in the examples of WO 2010/063612 A1.

Also suitable are nonyellowing or low-yellowing photoinitiators of thephenylglyoxalic ester type, such as silsesquioxane compounds describedin DE-A 198 26 712, DE-A 199 13 353 or WO 98/33761.

Preference among these photoinitiators is given to2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, ethyl2,4,6-trimethylbenzoylphenylphosphinate,bis(2,4,6-tri-methylbenzoyl)phenylphosphine oxide,2-benzyl-2-dimethylamino-4′-morpholinobutyrophenone,2-(dimethylamino)-1-(4-morpholinophenyl)-2-(p-tolylmethyl)butan-1-one,2-hydroxy-1-[4-[[4-(2-hydroxy-2-methyl-propanoyl)phenyl]methyl]phenyl]-2-methylpropan-1-one,and also the above-described polymeric thioxanthone and benzophenonederivatives, and also those described in WO 2010/063612 A1.

As further additives typical for printing-inks it is possible forexample to use dispersants, waxes, stabilizers, sensitizers, fillers,defoamers, colorants, antistatic agents, thickeners, surface-activeagents such as flow control agents, slip aids or adhesion promoters.

Suitable fillers comprise silicates, examples being silicates obtainableby hydrolysis of silicon tetrachloride, such as Aerosil® from Degussa,siliceous earth, talc, aluminum silicates, magnesium silicates, calciumcarbonates, etc.

Recited below are examples of particularly suitable pigments.

Organic Pigments:

-   -   Monoazo pigments: C.I. Pigment Brown 25; C.I. Pigment Orange 5,        13, 36 and 67; C.I. Pigment Red 1, 2, 3, 5, 8, 9, 12, 17, 22,        23, 31, 48:1, 48:2, 48:3, 48:4, 49, 49:1, 52:1, 52:2, 53, 53:1,        53:3, 57:1, 63, 112, 146, 170, 184, 210, 245 and 251; C.I.        Pigment Yellow 1, 3, 73, 74, 65, 97, 151 and 183;    -   Disazo pigments: C.I. Pigment Orange 16, 34 and 44; C.I. Pigment        Red 144, 166, 214 and 242; C.I. Pigment Yellow 12, 13, 14, 16,        17, 81, 83, 106, 113, 126, 127, 155, 174, 176 and 188;    -   Anthanthrone pigments: C.I. Pigment Red 168 (C.I. Vat Orange 3);    -   Anthraquinone pigments: C.I. Pigment Yellow 147 and 177; C.I.        Pigment Violet 31;    -   Anthraquinone pigments: C.I. Pigment Yellow 147 and 177; C.I.        Pigment Violet 31;    -   Anthrapyrimidine pigments: C.I. Pigment Yellow 108 (C.I. Vat        Yellow 20);    -   Quinacridone pigments: C.I. Pigment Red 122, 202 and 206; C.I.        Pigment Violet 19;    -   Quinophthalone pigments: C.I. Pigment Yellow 138;    -   Dioxazine pigments: C.I. Pigment Violet 23 and 37;    -   Flavanthrone pigments: C.I. Pigment Yellow 24 (C.I. Vat Yellow        1);    -   Indanthrone pigments: C.I. Pigment Blue 60 (C.I. Vat Blue 4) and        64 (C.I. Vat Blue 6);    -   Isoindoline pigments: C.I. Pigment Orange 69; C.I. Pigment Red        260; C.I. Pigment Yellow 139 and 185;    -   Isoindolinone pigments: C.I. Pigment Orange 61; C.I. Pigment Red        257 and 260; C.I. Pigment Yellow 109, 110, 173 and 185;    -   Isoviolanthrone pigments: C.I. Pigment Violet 31 (C.I. Vat        Violet 1);    -   Metal complex pigments: C.I. Pigment Yellow 117, 150 and 153;        C.I. Pigment Green 8;    -   Perinone pigments: C.I. Pigment Orange 43 (C.I. Vat Orange 7);        C.I. Pigment Red 194 (C.I. Vat Red 15);    -   Perylene pigments: C.I. Pigment Black 31 and 32; C.I. Pigment        Red 123, 149, 178, 179 (C.I. Vat Red 23), 190 (C.I. Vat Red 29)        and 224; C.I. Pigment Violet 29;    -   Phthalocyanine pigments: C.I. Pigment Blue 15, 15:1, 15:2, 15:3,        15:4, 15:6 and 16; C.I. Pigment Green 7 and 36;    -   Pyranthrone pigments: C.I. Pigment Orange 51; C.I. Pigment Red        216 (C.I. Vat Orange 4);    -   Thioindigo pigments: C.I. Pigment Red 88 and 181 (C.I. Vat Red        1); C.I. Pigment Violet 38 (C.I. Vat Violet 3);    -   Triarylcarbonium pigments: C.I. Pigment Blue 1, 61 and 62; C.I.        Pigment Green 1; C.I. Pigment Red 81, 81:1 and 169; C.I. Pigment        Violet 1, 2, 3 and 27; C.I. Pigment Black 1 (aniline black);        C.I. Pigment Yellow 101 (aldazine yellow);

C.I. Pigment Brown 22. Inorganic Pigments:

-   -   White pigments: titanium dioxide (C.I. Pigment White 6), zinc        white, pigmented zinc oxide, barium sulfate, zinc sulfide,        lithopones; lead white; calcium carbonate;    -   Black pigments: iron oxide black (C.I. Pigment Black 11),        iron-manganese black, spinel black (C.I. Pigment Black 27);        carbon black (C.I. Pigment Black 7);    -   Color pigments: chromium oxide, chromium oxide hydrate green;        chromium green (C.I. Pigment Green 48); cobalt green (C.I.        Pigment Green 50); ultramarine green; cobalt blue (C.I. Pigment        Blue 28 and 36); ultramarine blue; iron blue (C.I. Pigment Blue        27); manganese blue; ultramarine violet; cobalt and manganese        violet; iron oxide red (C.I. Pigment Red 101); cadmium        sulfoselenide (C.I. Pigment Red 108); molybdate red (C.I.        Pigment Red 104); ultramarine red;        Iron oxide brown, mixed brown, spinel and corundum phases (C.I.        Pigment Brown 24, 29 and 31), chromium orange;        Iron oxide yellow (C.I. Pigment Yellow 42); nickel titanium        yellow (C.I. Pigment Yellow 53; C.I. Pigment Yellow 157 and        164); chromium titanium yellow; cadmium sulfide and cadmium zinc        sulfide (C.I. Pigment Yellow 37 and 35); chromium yellow (C.I.        Pigment Yellow 34), zinc yellow, alkaline earth metal chromates;        Naples yellow; bismuth vanadate (C.I. Pigment Yellow 184);    -   Interference pigments: metallic effect pigments based on coated        metal platelets; pearlescent pigments based on metal oxide        coated mica platelets; liquid crystal pigments.

Preferred pigments (B) in this context are monoazo pigments (especiallylaked BONS pigments, Naphthol AS pigments), disazo pigments (especiallydiaryl yellow pigments, bisacetoacetanilide pigments, disazopyrazolonepigments), quinacridone pigments, quinophthalone pigments, perinonepigments, phthalocyanine pigments, triarylcarbonium pigments (alkaliblue pigments, laked rhodamines, dye salts with complex anions),isoindoline pigments, white pigments, and carbon blacks.

Examples of particularly preferred pigments (B) are specifically: carbonblack, titanium dioxide, C.I. Pigment Yellow 138, C.I. Pigment Red 122and 146, C.I. Pigment Violet 19, C.I. Pigment Blue 15:3 and 15:4, C.I.Pigment Black 7, C.I. Pigment Orange 5, 38 and 43 and C.I. Pigment Green7.

Suitable stabilizers comprise typical UV absorbers such as oxanilides,triazines, and benzotriazole (the latter obtainable as Tinuvin® gradesfrom BASF), and benzophenones. They can be employed alone or togetherwith suitable free-radical scavengers, examples being stericallyhindered amines such as 2,2,6,6-tetramethylpiperidine,2,6-di-tert-butylpiperidine or derivatives thereof, e.g.,bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, or quinone methide (suchas Irgastab® UV22). Stabilizers are used usually in amounts of 0.1% to0.5% by weight of the active ingredient component based on thepreparation.

A further aspect of the present invention is a process for printingsheetlike or three-dimensional, preferably sheetlike substrates by anydesired printing process, using at least one printing-ink of theinvention. In one preferred variant of the printing process of theinvention, at least one printing-ink of the invention is printed onto asubstrate and then treated with actinic radiation, as for example UVradiation and/or electron beams, preferably UV radiation.

Printing processes in which the printing-inks of the invention can beused are preferably offset printing, letterpress, flexographic printing,gravure printing, screen printing, and inkjet printing, more preferablyflexographic and offset printing.

In the so-called mechanical printing processes such as offset printing,letterpress, flexographic printing or gravure printing, the printing-inkis transferred to the print-receiving medium (printing stock) by contactwith a printing form or printing plate which is inked with printing-ink.UV-curable printing-inks for these applications typically comprisereactive diluents, binders, colorants, initiators, and also, optionally,various additives. Binders serve to form the ink film and to anchor theconstituents, such as pigments or fillers, for example, in the ink film.Depending on consistency, printing-inks for these applications typicallycomprise between 10% and 60% by weight of binder. Reactive diluentsserve to adjust the processing viscosity.

Print varnishes are applied either to the printing stock, as a primer,or to the printing stock after the printing operation, as a coating.Print varnishes are used, for example, for protecting the printed image,for improving the adhesion of the printing-ink to the printing stock, orfor esthetic purposes. Application is typically in-line or off-line bymeans of a varnishing unit on the printing machine.

Print varnishes contain no colorant, but apart from that generally havea similar composition to printing-inks, and are distinguished by theabsence of the colorant.

Printing-inks for mechanical printing processes comprise what are calledpasty printing-inks of high viscosity for offset printing and forletterpress, and also what are called liquid printing-inks, ofcomparatively low viscosity, for flexographic and gravure printing.

The inks of the invention can be used for example as ink-jet liquid andalso for liquid toners for electrophotographic printing processes.

Optionally, if two or more printed layers of the printing-inks areapplied one above another, it is possible for drying and/or radiationcuring to take place after each printing operation.

Radiation curing takes place with high-energy light, UV light forexample, or electron beams. Radiation curing may also take place atrelatively high temperatures.

Examples of suitable radiation sources for the radiation cure arelow-pressure mercury lamps, medium-pressure mercury lamps withhigh-pressure lamps, and fluorescent tubes, pulsed lamps, metal halidelamps, electronic flash units, with the result that radiation curing ispossible without a photoinitiator, or excimer lamps and also UV LEDs.The radiation cure is accomplished by exposure to high-energy radiation,i.e., UV radiation, or daylight, preferably light in the wavelengthrange of λ=200 to 700 nm, more preferably λ=200 to 500 nm, and verypreferably λ=250 to 400 nm, or by exposure to high-energy electrons(electron beams; 60 to 300 keV). Examples of radiation sources usedinclude high-pressure mercury vapor lamps, lasers, pulsed lamps (flashlight), halogen lamps, UV LEDs, or excimer lamps. The radiation dosenormally sufficient for crosslinking in the case of UV curing is in therange from 30 to 3000 mJ/cm².

It will be appreciated that a number of radiation sources can also beused for the cure: two to four, for example.

These sources may also emit each in different wavelength ranges.

Irradiation can optionally also be carried out in the absence of oxygen,such as under an inert gas atmosphere. Suitable inert gases arepreferably nitrogen, noble gases, carbon dioxide, or combustion gases.

It is an advantage of the polyurethanes (A) and of the process of theinvention that they can be used to prepare inks, printing-inks, andprint varnishes whose levels of extractable and/or migratableconstituents are reduced. Since the photoinitiator is incorporated intothe polyurethanes of the invention, the degradation products of thephotoinitiators as well are additionally fixed in the coating, and sogenerally have little or no migration capacity. A consequence of this isthat with the polyurethanes of the invention, little or no migratablefraction of degradation products of photoinitiators is found, when theresulting coatings are subjected to extraction, for example, bycomparison with coatings which require the addition of photoinitiatorsof low molecular mass—that is, photoinitiators which are notincorporable. By foregoing the use of tin as catalyst in the preparationof the polyurethanes (A), toxicologically objectionable metals areavoided. Moreover, the viscosity of the formulations, inks,printing-inks, and print varnishes of the invention is generallyrelatively low, since the polyurethanes preferably contain allophanategroups. Moreover, as a result of the fraction of water, it is possibleto prepare a low-viscosity formulation, which facilitates incorporationof the polyurethanes (A) into inks, print varnishes, and printing-inks.

ppm and percentage figures used in this specification are by weightunless otherwise indicated.

The examples below are intended to illustrate the invention but not tolimit it to these examples.

EXAMPLES

Laromer® LR 8863 of BASF SE, Ludwigshafen, is a commercial triacrylateof trimethylolpropane which has on average 3.5-fold ethoxylation.

Laromer® 9000 from BASF SE, Ludwigshafen, is a commercial polyisocyanatecontaining allophanate groups, of formula (I) above, in which acrylategroups are bonded via allophanate groups. The NCO content is 14.5% to15.5% by weight.

Irgacure® 2959 from BASF SE, Ludwigshafen, is a commercialphotoinitiator of the α-hydroxy ketone type(1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one).

Irgastab® UV22 from BASF SE, Ludwigshafen, is a commercial stabilizercomprising quinone methide in solution in an acrylate of propoxylatedglycerol.

Example 1

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), 0.1 part of Borchi® Kat 24 (bismuth carboxylate), and0.9 part of a further stabilizer (Irgastab® UV22) were introduced into areaction flask and heated to 80° C. They were then reacted at 80-85° C.until the NCO value had dropped to <0.8%, whereupon the equivalentamount of ethanol was added, calculated relative to NCO, and reactionwas continued until the NCO value had dropped to 0. The batch was thencooled, admixed with 3% of water, and discharged.

Example 1a

86 parts of a polyether acrylate (Laromer® LR 8863), 100 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), 0.1 part of Borchi® Kat 24 (bismuth carboxylate), and0.9 part of a further stabilizer (Irgastab®UV22) were introduced into areaction flask and heated to 80° C. They were then reacted at 80-85° C.until the NCO value had dropped to <0.8%, whereupon the equivalentamount of ethanol was added, calculated relative to NCO, and reactionwas continued until the NCO value had dropped to 0. The batch was thencooled, admixed with 3% of water, and discharged. The GPC spectrum showsthat there is still about 6% of unreacted Irgacure® 2959 present.

Comparative Example 1

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), and 79 parts of a photoinitiator(Irgacure® 2959), were introduced into a reaction flask and heated to80° C. Reaction was then continued at 80-85° C. to bring the NCO valueto <0.8%. After about 20 hours, the photoinitiator had still notcompletely reacted. Before the value reached <0.8% (about 12 hours),however, crosslinking occurred.

Comparative example 1 shows that it is necessary to react the free NCOgroups with a component (f).

Comparative Example 2

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), and 0.9 part of a further stabilizer (Irgastab® UV22)were introduced into a reaction flask and heated to 80° C. They werethen reacted at 80-85° C. until the NCO value had dropped to <0.8%,whereupon the equivalent amount of ethanol was added, calculatedrelative to NCO, and reaction was continued until the NCO value haddropped to 0. The batch was then cooled and admixed with 5% of water.The reaction mixture became cloudy.

Comparative example 2 shows that the formulations of the invention turncloudy if too much water is added.

Example 2

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), 50 ppm of Borchi® Kat 24 (bismuth carboxylate), and0.015 part of a further stabilizer (Irgastab® UV22) were introduced intoa reaction flask and heated to 80° C. They were then reacted at 80-85°C. until the NCO value had dropped to <0.8%, whereupon the equivalentamount of ethanol was added, calculated relative to NCO, and reactionwas continued until the NCO value had dropped to 0. The GPC chromatogramshowed complete reaction of the photoinitiator. Then a further part ofthe UV22 stabilizer was added and the batch was cooled, admixed with 2%of water, and discharged.

Example 3

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), 50 ppm of Borchi® Kat 22 (zinc carboxylate), and 0.015part of a further stabilizer (Irgastab®UV22) were introduced into areaction flask and heated to 80° C. They were then reacted at 80-85° C.until the NCO value had dropped to <0.8%, whereupon the equivalentamount of ethanol was added, calculated relative to NCO, and reactionwas continued until the NCO value had dropped to 0. The GPC chromatogramshowed complete reaction of the photoinitiator. Then 1.5 further partsof the UV22 stabilizer were added and the batch was cooled, admixed with2% of water, and discharged.

Example 4

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), 50 ppm of tetrabutyl orthotitanate, and 0.015 part ofa further stabilizer (Irgastab® UV22) were introduced into a reactionflask and heated to 80° C. They were then reacted at 80-85° C. until theNCO value had dropped to <0.8%, whereupon the equivalent amount ofethanol was added, calculated relative to NCO, and reaction wascontinued until the NCO value had dropped to 0. The GPC chromatogramshowed complete reaction of the photoinitiator. Then 1.5 further partsof the UV22 stabilizer were added and the batch was cooled, admixed with2% of water, and discharged.

Example 5

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), 50 ppm of Borchi® Kat 315 (bismuth carboxylate), and0.015 part of a further stabilizer (Irgastab® UV22) were introduced intoa reaction flask and heated to 80° C. They were then reacted at 80-85°C. until the NCO value had dropped to <0.8%, whereupon the equivalentamount of ethanol was added, calculated relative to NCO, and reactionwas continued until the NCO value had dropped to 0. The GPC chromatogramshowed complete reaction of the photoinitiator. Then 1.5 further partsof the UV22 stabilizer were added and the batch was cooled, admixed with2% of water, and discharged.

Example 6

86 parts of a polyether acrylate (Laromer® LR 8863), 120 parts of anisocyanato acrylate (Laromer® LR9000), 79 parts of a photoinitiator(Irgacure® 2959), 50 ppm of Borchi® Kat 315 (bismuth carboxylate), and0.015 part of a further stabilizer (Irgastab® UV22) were introduced intoa reaction flask and heated to 80° C. They were then reacted at 80-85°C. until the NCO value had dropped to <0.8%, whereupon the equivalentamount of Lutensol TO3 (C13 alcohol ethoxylate, BASF SE) was added,calculated relative to NCO, and reaction was continued until the NCOvalue had dropped to 0. The GPC chromatogram showed complete reaction ofthe photoinitiator. Then 1.5 further parts of the UV22 stabilizer wereadded and the batch was cooled, admixed with 2% of water, anddischarged.

USE EXAMPLES Example 7

A product was prepared in analogy to example 1, as a 70% strength byweight solution in Laromer® LR 8863, without addition of water, and wasmixed with different amounts of water, followed by examination of theappearance and the viscosity.

Viscosity Fluidity at at 25° C. 25° C. Miscibility none 600 Pas no clear1% water 322 Pas poor clear 2% water 170 Pas good clear 5% water  82 Pasvery good cloudy

It is seen that without the addition of water, the formulation is notfluid, and on addition of too much water, it turns cloudy. There istherefore a narrow window remaining, within which both the viscosity andthe performance properties are favorable.

Example 8

Various incorporable photoinitiators in accordance with the presentinvention and in accordance with DE 10 2006 047863 were prepared andwere formulated with radiation-curable acrylates to give a printvarnish.

Example 5 from DE 10 2006 047863 was repeated and was considered as pureinitiator, based on its photoinitiator content (comparative a), or ascoating material, based on its reactive diluent content (comparative c).

Using the formulations, determinations were made of the cure rate,viscosity, gloss, abrasion stability, and solvent resistance.

For this purpose, the varnish was coated using a 6 μm wire doctor onto aLeneta card, and exposed using a M-30-2×1-BLKU UV unit from IST, whichis equipped with a 200 W/cm Hg medium-pressure lamp with adjustablepower. The cure rate was determined using the fingernail. When thesurface showed no scratches, the varnish was considered to be cured.

The gloss was determined at 60° on Leneta card using a Byk-Gardnermicro-tri-gloss gloss meter. After 5 double rubs (back and forth) with aScotch Brite® 07448 pad (from 3M), the abrasion resistance wasdetermined by means of the drop in gloss.

Comparative a Comparative b Inventive Comparative c Example 5 from 15.0DE 10 2006 047863 Example 2 from 15 DE 10 2006 047863 (i.e., no water)Example 5, i.e., 15.0 containing 2% by weight water Example 5 from 100 DE 10 2006 047863 Laromer ® LR 8986 27 27 27 Laromer ® PO77F 33 33 33Tripropylene glycol 39.8 39.8 39.8 diacrylate EFKA 7305 0.2 0.2 0.2 Sumtotal 100 100 100 Cure rate 3 m/min 18 m/min 15 m/min 5 m/min Viscosityof reaction 0.2 Pas 600 Pas 170 Pas — mixture Viscosity of coating 0.3Pas 0.6 Pas 0.4 Pas 0.2 Pas material Gloss 85 92 92 70 Abrasionresistance 49 77 77 61 (residual gloss after 5 double rubs with ScotchBrite 07448 (3M)) MEK resistance <10 30 30 30 double rubs Laromer ® LR8986 is a commercial mixture of epoxy acrylate and triacrylate ofethoxylated trimethylolpropane, from BASF SE, Ludwigshafen. Laromer ® PO77F is a commercial, amine-modified, approximately trifunctionalpolyether acrylate from BASF SE, Ludwigshafen. EFKA 7305 is a commercialadditive for flow and surface smoothness, from BASF SE, Ludwigshafen.

It is seen that in the inventive example it is possible to lower theviscosity even of the print varnish by addition of water. In comparativeb, however, the reaction mixture according to example 2 from DE 10 2006047863 (i.e., no water) is not fluid and is therefore difficult toformulate, and also the viscosity of the print varnish is too high foran optimum coating outcome.

From comparatives a and c it is apparent that example 5 from DE 10 2006047863, in direct comparison with the inventive example, exhibits poorerperformance properties, such as a lower residual gloss and poorerabrasion resistance, and has inadequate reactivity.

Example 9

The photoinitiators of the invention from example 5 (in example 9a), andexample 6 (in example 9b) were used in an offset printing-ink, withIrgacure® 2959 selected as comparative. The concentration of Irgacure®2959 in the comparative example corresponded to the concentration of thechromophore in the photoinitiator of the invention. All of thecomponents were mixed and dispersed on a Bühler laboratory roll mill,until all of the photoinitiators had dissolved.

The printing-ink was then printed with a coat weight of 1.7 g/m² ontocoated cardboard, using an offset sample printing instrument fromPrüfbau, and exposed using a M-30-2×1-BLKU UV exposure unit from IST at80 W/cm (aluminum reflectors). Through-cure was determined using the RELTester (PTC instrument, from Prüfbau). The colored density wasdetermined using an SPM55 densitometer from GretagMacbeth.

Ex. 9a Ex. 9b Comparative Heliogen Blue D7088 16 16 16 Ebecryl 657 19 1920 Ebecryl 3700 17 17 18 Laromer ® PE 9084 19 19 20 Laromer ® GPTA 16 1619 Luwax ® AF30 1 1 1 Irgacure ® 369 4 4 4 Irgacure ® 2959 2 Initiatorfrom example 5 8 Initiator from example 6 8 Sum total 100 100 100 Curerate m/min 180 180 130 Color density of print 1.41 1.53 1.37

Surprisingly it is found that the initiators of the invention, for thesame chromophore concentration, in fact have a markedly higher cure ratethan the comparative example. The color density, as a measure of theintensity of the colored print, is in fact higher for example 9b, wherea fatty acid alcohol was used, than in the case of the otherexperiments, which points additionally to a dispersing of thephotoinitiator of the invention.

1. A process for preparing an incorporable photoinitiator of lowviscosity, the process comprising 1) synthesizing a polyurethane Acomprising, in reacted form: (a) an organic polyisocyanate comprising anallophanate group and having an NCO functionality of at least 2,synthesized from an aliphatic C₄ to C₂₀ alkylene diisocyanate, (b) acompound having at least one isocyanate-reactive group and at least oneradically polymerizable unsaturated group, (c) a photoinitiator havingat least one isocyanate-reactive group, (d) optionally a furtherdiisocyanate, polyisocyanate, or both, which is different from (a), (e)optionally a compound having at least two isocyanate-reactive groups,and (f) optionally a compound having precisely one isocyanate-reactivegroup, under an anhydrous condition, in the presence of less than 1000ppm by weight of a compound comprising at least one element selectedfrom the group consisting of bismuth, zinc and titanium, to obtain thepolyurethane A; and 2) mixing the polyurethane A with 0.5% to 4% byweight of water, based on an amount of the polyurethane A.
 2. Theprocess according to claim 1, wherein component (b) is bonded viaallophanate groups to component (a).
 3. The process according to claim2, wherein an amount of allophanate groups, calculated as C₂N₂HO₃=101g/mol, is 1% to 28% by weight.
 4. The process according to claim 1,wherein the compound (c) has at least one formula selected from thegroup consisting of

in which R³, R⁴, and R⁵ each independently of one another are hydrogen,an alkyl group comprising 1 to 4 carbon atoms or an alkyloxy groupcomprising 1 to 4 carbon atoms, p is 0 or an integer from 1 to 10, andY_(i) for i=1 to p independently of one another are selected from thegroup consisting of —CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, —CH(CH₃)—CH₂—O—,—CH₂—C(CH₃)₂—O—, —C(CH₃)₂—CH₂—O—, —CH₂—CHVin-O—, —CHVin-CH₂—O—,—CH₂—CHPh-O—, and —CHPh-CH₂—O—.
 5. The process according to claim 1,wherein the compound (c) is selected from the group consisting of2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxycyclohexyl phenylketone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one,2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)benzyl]phenyl}-2-methylpropan-1-one,2-hydroxy-1-[4-[hydroxy[4-(2-hydroxy-2-methylpropanoyl)phenyl]methyl]phenyl]-2-methyl-propan-1-one,[4-[3-(4-benzoylphenoxy)-2-hydroxypropoxy]phenyl]phenylmethanone,benzoin, benzoin isobutyl ether, benzoin tetrahydropyranyl ether,benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoinisopropyl ether, 7H-benzoin methyl ether,2-hydroxy-2,2-dimethylacetophenone, and 1-hydroxyacetophenone.
 6. Theprocess according to claim 1, wherein the polyurethane A comprises, inreacted form, a compound (f) comprising an alkoxylated aliphatic alcoholhaving a formulaR⁹—O—[—Z_(i)—]_(z)—H in which R⁹ is an alkyl radical having 1 to 20carbon atoms, q is a positive integer from 1 to 15, and Z_(i) for i=1 toq independently of one another are selected from the group consisting of—CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, —CH(CH₃)—CH₂—O—, —CH₂—C(CH₃)₂—O—,—C(CH₃)₂—CH₂—O—, —CH₂—CHVin-O—, —CHVin-CH₂—O—, —CH₂—CHPh-O—, and—CHPh-CH₂—O—.
 7. The process according to claim 1, wherein compoundcomprising at least one element selected from the group consisting ofbismuth, zinc and titanium is selected from the group consisting of azinc carboxylate of a carboxylate which has at least six carbon atoms, abismuth carboxylate of a carboxylate which has at least six carbonatoms, and a titanium tetraalcoholate, Ti(OR)₄ of an alcohol ROH having1 to 8 carbon atoms.
 8. A formulation of an incorporable photoinitiator,comprising: a polyurethane A, 0.5% to 4% by weight of water, based on anamount of the polyurethane A, and optionally a polyfunctionalpolymerization compound B, wherein the polyurethane A comprises, inreacted form: (a) an organic polyisocyanate comprising an allophanategroup and having an NCO functionality of at least 2, synthesized from analiphatic C₄ to C₂₀ alkylene diisocyanate, (b) a compound having atleast one isocyanate-reactive group and at least one radicallypolymerizable unsaturated group, (c) a photoinitiator having at leastone isocyanate-reactive group, (d) optionally a further diisocyanate,polyisocyanate, or both, which is different from (a), (e) optionally acompound having at least two isocyanate-reactive groups, and (f)optionally a compound having precisely one isocyanate-reactive group. 9.An ink, printing-ink or print varnish comprising the formulation ofclaim 8, optionally a pigment, the polyfunctional polymerizable compoundB, optionally a further photoinitiator, and optionally an additive. 10.The ink, printing-ink or print varnish according to claim 9, comprisingthe further photoinitiator, which is selected from the group consistingof 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl2,4,6-trimethylbenzoylphenylphosphinate,bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide,2-benzyl-2-dimethylamino-4′-morpholinobutyrophenone,2-(dimethylamino)-1-(4-morpholinophenyl)-2-(p-tolylmethyl)butan-1-one,2-hydroxy-1-[4-[[4-(2-hydroxy-2-methylpropanoyl)phenyl]methyl]phenyl]-2-methylpropan-1-one,a polymeric benzophenone derivative, a polymeric thioxanthonederivative, a polymeric α-amino ketone, and a silsesquioxane compoundhaving at least one initiating group.
 11. A method of printing on amaterial selected from the group consisting of polyamide, polyethylene,polypropylene, polyester, polyethylene terephthalate, polystyrene,paper, paperboard, cardboard, plastics-coated paper, plastics-coatedpaperboard, plastics-coated cardboard, aluminum, and an aluminum-coatedpolymeric, the method comprising contacting the printing ink of claim 10with the material.
 12. The method according to claim 11, wherein thematerial is a food packaging material, a cosmetic packaging material, ora pharmaceutical packaging material.
 13. A polyurethane A comprising, inreacted form: (a) an organic aliphatic, aromatic or cycloaliphaticdiisocyanate or polyisocyanate having a functionality of more than 2,(b) a compound having at least one isocyanate-reactive group and atleast one radically polymerizable unsaturated group, (c) aphotoinitiator having at least one isocyanate-reactive group, (d)optionally a further diisocyanate, polyisocyanate, or both, which isdifferent from (a), (e) optionally a compound having at least twoisocyanate-reactive groups, and (f) optionally a compound havingprecisely one isocyanate-reactive group, wherein the compound (f)comprises an alkoxylated aliphatic alcohol having a formulaR⁹—O—[—Z_(i)—]_(q)—H in which R⁹ is an alkyl radical having 1 to 20carbon atoms, q is a positive integer from 1 to 15, and Z_(i) for i=1 toq independently of one another are selected from the group consisting of—CH₂—CH₂—O—, —CH₂—CH(CH₃)—O—, —CH(CH₃)—CH₂—O—, —CH₂—C(CH₃)₂—O—,—C(CH₃)₂—CH₂—O—, —CH₂—CHVin-O—, —CHVin-CH₂—O—, —CH₂—CHPh-O—, and—CHPh-CH₂—O—.
 14. The process according to claim 1, wherein thepolyurethane A comprises, in reacted form, (d) the further diisocyanate,polyisocyanate, or both, which is different from (a).
 15. The processaccording to claim 1, wherein the polyurethane A comprises, in reactedform, (e) the compound having at least two isocyanate-reactive groups.16. The process according to claim 1, wherein the polyurethane Acomprises, in reacted form, (f) the compound having precisely oneisocyanate-reactive group.
 17. The process according to claim 1, whereinthe polyurethane A comprises, in reacted form, (d) and (e).
 18. Theprocess according to claim 1, wherein the polyurethane A comprises, inreacted form, (d) and (f).
 19. The process according to claim 1, whereinthe polyurethane A comprises, in reacted form, (e) and (f).
 20. Theprocess according to claim 1, wherein the polyurethane A comprises, inreacted form, (d), (e) and (f).